The study and treatment of many cardiopulmonary diseases are limited by the ability to express specific recombinant genes in nondividing cells in vivo. Gene transfer is the introduction of foreign DNA or gene sequences into host somatic cells, and this method facilitates in vivo investigations of gene expression and function. Delivery of recombinant genes into the pulmonary vasculature could potentially result in the expression of recombinant genes in large number of cells, including endothelial cells, type II pneumocytes, and distal airway epithelial cells. The expression of genes in these cells could facilitate investigations of the pathobiology of pulmonary vascular diseases and the potential development of gene therapy approaches to treat These vascular diseases. The purpose of this grant is to test the hypothesis that recombinant genes can be delivered and expressed in the pulmonary vasculature in vivo. In Specific Aim I, recombinant reporter genes will be introduced into the pulmonary vasculature using adenoviral and DNA liposome vectors, gene expression will be confirmed by analysis of DNA, mRNA and protein; cell types which are transduced will be defined; and the duration of gene expression in the lung and other tissues will be investigated. In Specific Aim II, modifications will be made in these vectors to optimize transfection efficiencies and gene expression in vivo. Lung specific gene expression will be developed using surfactant promoters. In Specific Aim III, the hypothesis that recombinant genes may persist longer in neonatal tissue compared with adult tissue will be tested by investigations into the stability of gene expression following gene transfer with adenoviral and DNA liposome vectors into neonatal and adult lungs. Preliminary studies in our laboratory demonstrate the feasibility of these studies. In a porcine animal model, we have shown that recombinant reporter genes can be expressed at specific sites in the pulmonary vasculature following transcatheter injection. In a human gene therapy phase I study, transcatheter delivery of HLA-B7 DNA and liposomes into a right posterior basal segment artery was safely performed in a patient with melanoma metastatic to the right lower lobe. The goal of this proposal is to optimize the delivery and expression of recombinant genes in the pulmonary vasculature following direct gene transfer with adenoviral and DNA liposome vectors. In addition, developmental differences in gene expression will be investigated in neonatal and adult lungs. The ability to express these recombinant genes at an early age may allow for early interventions designed to prevent the progression of pulmonary diseases. Taken together, these studies should provide insight into basic mechanisms of gene expression within pulmonary tissue and may provide an approach to the genetic treatment of pulmonary vascular diseases.